Allowable Foundation Settlement for Different Structures

The allowable settlement is defined as the acceptable amount of settlement of the structure and it usually includes a factor of safety.

Allowable below shows the allowable foundation displacement into three categories: total settlement, tilting, and differential settlement.

It indicates that those structures that are more flexible (such as simple steel frame buildings) or have more rigid foundations (such as mat foundations) can sustain larger values of total settlement and differential movement.

Type of Settlement	Limiting factor	Maximum Settlement
Total settlement	Drainage	15 – 30 cm
	Access	30 – 60 cm
	Probability of non-uniform settlement:
	1. Masonry walled structures	2.5 – 5 cm
	2. Framed structures	5 – 10 cm
	3. Chimneys, silos, mats	8 – 30 cm
Tilting	Stability against overturning	Depends on H and L
	Tilting of chimneys, towers	0.004L
	Rolling of trucks etc.	0.01L
	Stacking of goods	0.01L
	Crane rails	0.003L
	Drainage of floors	0.01 – 0.02 L
Differential settlement	High continuous brick walls	0.0005 – 0.001 L
	One-storey brick mill building, wall cracking	0.001 – 0.002 L
	Plaster cracking	0.001 L
	Reinforced concrete building frame	0.0025 – 0.004 L
	Reinforced concrete building curtain walls	0.003 L
	Steel frame, continuous	0.002 L
	Simple steel frame	0.005 L

Where, L = distance between adjacent columns that settle to different amounts, or between two points that settle differently. Higher values are for regular settlements and more tolerant structures. Lower values are for irregular settlement and critical structures. H = Height and W = width of structure.